镀液成分对纳米镍-钴合金镀层显微硬度的影响

Effects of Electrolyte Composition on Micro-hardness of Nano Ni-Co Alloy Coatings

研究了镀液成分(糖精和钴)对脉冲电沉积纳米镍-钴合金镀层显微结构和显微硬度的影响。结果发现:镀液中糖精和钴的加入都可以细化晶粒,提高硬度;同时其质量浓度的进一步增加又都可以使镀层硬度下降。通过镀液中钴的加入,有机晶粒细化剂(糖精)的用量可以明显减小,这将有助于镀层性能的提高。由于糖精的过量使用会使镀层中硫和碳的杂质量增加,而这些杂质往往存在于晶界上,使镀层韧性下降。

The effects of the electrolyte ingredients, i. e. , saccharin and cobalt, on the micro-hardness and microstructure of pulse plated nano Ni-Co alloys are investigated. It is found that both saccharin and cobalt, when added to the electrolyte, can lead to a higher hardness and finer structure of the deposit, whereas further increase in their mass concentration will decline the coating hardness. By adding Co^2＋ ions to the electrolyte, the amount of organic refiner saccharin needed to produce nanocrystalline structure deposit can be reduced remarkably, which is helpful for improvement of coating performances, because overdose of saccharin will increase the impurities of sulfur and carbonate, which usually stay on crystalline grain boundaries, reducing deposit ductility.